The present invention relates to a new acrylic derivative of urea.
Acrylic derivatives of urea are already known. The acrylic compounds used as starting substances are most often acrylamide and acrylonitrile. Thus, the polycondensation of urea, formaldehyde and acrylamide in a weakly alkaline medium with a view to preparing methylolated products, followed by the addition of styrene or methyl acrylate, has been proposed (in particular, Kostyukov et al--USSR 277,550, 3 June 1970). The preparation of acrylic derivatives of urea from methacrylamide, formaldehyde and urea has also been proposed (French Application 85/06,106). A new process for manufacturing acrylamidomethyleneurea has also been described (in French Application 85/06,103), which process consists in reacting, in a first stage, acrylamide with formaldehyde in a basic medium with a view to obtaining monomethylolacrylamide, and then, in a second stage, in reacting the latter compound with urea in an acid medium.
The present invention relates to a new acrylic derivative of urea, monomethylolacrylamidomethyleneurea.
This product has the following formula: ##STR1##
This product takes the form of a white solid which changes its physical state between 190 and 200.degree. C.
The new acrylic derivative of urea is prepared according to the following procedure. According to this procedure, acrylamidomethyleneurea, obtained according to the preparation process described in French Application 85/06,103, is employed. This process comprises a first step of reacting acrylamide with formaldehyde at a basic pH and then in a second step reacting the resultant product from the first step with urea at a pH of at most 4.5, the quantity of urea being preferably higher than 4 molar equivalents to one molar equivalent of the reaction product obtained in the first step.
To this resultant urea derivative, water and aqueous solution of formaldehyde are added. The reaction is carried out in the presence of an inhibitor such as hydroquinone methyl ether and triethylamine, heating for approximately one hour to 60.degree. C. A white precipitate is then formed after cooling, and is separated by filtration. The product is then purified by washing with ethyl acetate and then with acetone: it is then recrystallized in an ethyl acetate/ ethanol mixture.
The new acrylic derivative which is the subject of the invention is prepared using equimolecular quantities of acrylamidomethyleneurea and formaldehyde. It is especially useful as an additive in aminoplastic and phenoplastic resins, in particular those used as wood glues. In aminoplastics in particular, it is employed in the form of a solution in a urea/formaldehyde precondensate. In this case, the monomethylolacrylamidomethyleneurea dissolved in a urea/formaldehyde precondensate is prepared according to the procedures described in the above-cross-referenced application entitled "New Additives Suitable for use in Aminoplastic Resins." These procedures consist in preparing monomethylolacrylamidomethyleneurea either from acrylamide in a urea/formaldehyde precondensate, or from acrylamidomethyleneurea in a urea/formaldehyde precondensate.